From 33cf7c90fe2f97afb1cadaa0cfb782cb9d1b9ee2 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 11 Mar 2015 18:53:14 -0700 Subject: net: add real socket cookies A long standing problem in netlink socket dumps is the use of kernel socket addresses as cookies. 1) It is a security concern. 2) Sockets can be reused quite quickly, so there is no guarantee a cookie is used once and identify a flow. 3) request sock, establish sock, and timewait socks for a given flow have different cookies. Part of our effort to bring better TCP statistics requires to switch to a different allocator. In this patch, I chose to use a per network namespace 64bit generator, and to use it only in the case a socket needs to be dumped to netlink. (This might be refined later if needed) Note that I tried to carry cookies from request sock, to establish sock, then timewait sockets. Signed-off-by: Eric Dumazet Cc: Eric Salo Signed-off-by: David S. Miller --- net/core/sock.c | 1 + net/core/sock_diag.c | 37 +++++++++++++++++++++++++++---------- 2 files changed, 28 insertions(+), 10 deletions(-) (limited to 'net/core') diff --git a/net/core/sock.c b/net/core/sock.c index 726e1f99aa8d..a9a9c2ff9260 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1538,6 +1538,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority) newsk->sk_err = 0; newsk->sk_priority = 0; newsk->sk_incoming_cpu = raw_smp_processor_id(); + atomic64_set(&newsk->sk_cookie, 0); /* * Before updating sk_refcnt, we must commit prior changes to memory * (Documentation/RCU/rculist_nulls.txt for details) diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c index 96e70ee05a8d..74dddf84adcd 100644 --- a/net/core/sock_diag.c +++ b/net/core/sock_diag.c @@ -13,22 +13,39 @@ static const struct sock_diag_handler *sock_diag_handlers[AF_MAX]; static int (*inet_rcv_compat)(struct sk_buff *skb, struct nlmsghdr *nlh); static DEFINE_MUTEX(sock_diag_table_mutex); -int sock_diag_check_cookie(void *sk, const __u32 *cookie) +static u64 sock_gen_cookie(struct sock *sk) { - if ((cookie[0] != INET_DIAG_NOCOOKIE || - cookie[1] != INET_DIAG_NOCOOKIE) && - ((u32)(unsigned long)sk != cookie[0] || - (u32)((((unsigned long)sk) >> 31) >> 1) != cookie[1])) - return -ESTALE; - else + while (1) { + u64 res = atomic64_read(&sk->sk_cookie); + + if (res) + return res; + res = atomic64_inc_return(&sock_net(sk)->cookie_gen); + atomic64_cmpxchg(&sk->sk_cookie, 0, res); + } +} + +int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie) +{ + u64 res; + + if (cookie[0] == INET_DIAG_NOCOOKIE && cookie[1] == INET_DIAG_NOCOOKIE) return 0; + + res = sock_gen_cookie(sk); + if ((u32)res != cookie[0] || (u32)(res >> 32) != cookie[1]) + return -ESTALE; + + return 0; } EXPORT_SYMBOL_GPL(sock_diag_check_cookie); -void sock_diag_save_cookie(void *sk, __u32 *cookie) +void sock_diag_save_cookie(struct sock *sk, __u32 *cookie) { - cookie[0] = (u32)(unsigned long)sk; - cookie[1] = (u32)(((unsigned long)sk >> 31) >> 1); + u64 res = sock_gen_cookie(sk); + + cookie[0] = (u32)res; + cookie[1] = (u32)(res >> 32); } EXPORT_SYMBOL_GPL(sock_diag_save_cookie); -- cgit v1.2.3